added new Jenkins test to check for unwanted UTF8 files

Jenkinsfile

@@ -181,6 +181,13 @@ Changelog of Git Changelog.
         }
       }
 
+      stage('check for UTF-8 files') {
+        steps {
+          sh '''echo "$(find . -type f -exec file {} \\;)" > FileList
+            grep -v ASCII FileList | grep -v git'''
+        }
+      }
+
       stage('show diff') {
         steps {
           sh 'git diff'